U.S. patent application number 14/799763 was filed with the patent office on 2015-11-05 for method, system, and apparatus for diagnosing an exhaust aftertreatment component.
This patent application is currently assigned to CUMMINS IP, INC.. The applicant listed for this patent is Cummins IP, Inc.. Invention is credited to Tony James Hall.
Application Number | 20150315952 14/799763 |
Document ID | / |
Family ID | 51521032 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150315952 |
Kind Code |
A1 |
Hall; Tony James |
November 5, 2015 |
METHOD, SYSTEM, AND APPARATUS FOR DIAGNOSING AN EXHAUST
AFTERTREATMENT COMPONENT
Abstract
An apparatus includes an engine output module that determines an
engine output power parameter for an engine. The apparatus includes
an output power threshold module that determines if the engine
output power parameter is below an output power threshold. The
apparatus includes a NOx module that determines a nitrogen oxide
("NOx") efficiency of a selective catalytic reduction ("SCR")
system in response to the output power threshold module determining
that the determined engine output power parameter is below the
output power threshold. The SCR system is in exhaust receiving
communication with the engine. The apparatus includes a NO.sub.x
threshold module that determines if the NO.sub.x efficiency is
below a NO.sub.x efficiency threshold, and a NO.sub.x warning
module that sends a NO.sub.x alarm signal in response to the
NO.sub.x threshold module determining that the NO.sub.x efficiency
is below the NO.sub.x efficiency threshold.
Inventors: |
Hall; Tony James; (Bemus
Point, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cummins IP, Inc. |
Columbus |
IN |
US |
|
|
Assignee: |
CUMMINS IP, INC.
Columbus
IN
|
Family ID: |
51521032 |
Appl. No.: |
14/799763 |
Filed: |
July 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13934143 |
Jul 2, 2013 |
9109488 |
|
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14799763 |
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61788546 |
Mar 15, 2013 |
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Current U.S.
Class: |
60/274 ; 60/276;
73/23.31 |
Current CPC
Class: |
Y02T 10/24 20130101;
F01N 2550/02 20130101; Y02A 50/245 20180101; F01N 11/00 20130101;
F01N 2610/02 20130101; Y02T 10/40 20130101; F01N 2900/1621
20130101; F01N 3/2066 20130101; F01N 2900/1411 20130101; F01N 3/18
20130101; F01N 11/007 20130101; F01N 2900/1402 20130101; F01N
2550/05 20130101; G01N 33/0037 20130101; F02D 35/0015 20130101;
Y02A 50/20 20180101; Y02T 10/47 20130101; Y02T 10/12 20130101; F01N
2900/1818 20130101; F01N 3/208 20130101 |
International
Class: |
F01N 11/00 20060101
F01N011/00; F01N 3/20 20060101 F01N003/20; G01N 33/00 20060101
G01N033/00; F02D 35/00 20060101 F02D035/00 |
Claims
1. An apparatus comprising: a NO.sub.x change module structured to
determine an amount of change in a nitrogen oxide ("NO.sub.x")
efficiency of a selective catalytic reduction ("SCR") system within
a sampling window; a NO.sub.x change threshold module structured to
determine the amount of change in the NO.sub.x efficiency exceeds a
NO.sub.x efficiency change threshold; and a NO.sub.x warning module
structured to provide a NO.sub.x alarm in response to a NO.sub.x
efficiency below a NO.sub.x efficiency threshold and the amount of
change in the NO.sub.x efficiency exceeding the NO.sub.x efficiency
change threshold.
2. The apparatus of claim 1, further comprising: a NO.sub.x module
structured to determine the NO.sub.x efficiency in response to a
determined engine output power parameter below an output power
threshold.
3. The apparatus of claim 2, wherein the engine output power
parameter includes a level of exhaust flow and the output power
threshold includes an engine exhaust level threshold.
4. The apparatus of claim 2, wherein one or more of: the engine
output power parameter includes revolutions per minute ("RPM") of
an engine and the output power threshold includes an RPM threshold;
the engine output power parameter includes an engine power output
level of the engine and the output power threshold includes a level
of engine power output; the engine output power parameter includes
a temperature of the engine and the output power threshold includes
a temperature threshold; and the engine output power parameter
includes torque of the engine and the output power threshold
includes a torque threshold.
5. The apparatus of claim 2, wherein the NO.sub.x module determines
the NO.sub.x efficiency while the determined engine output power
parameter is within an engine output power range, the engine output
power range including a range below the output power threshold, and
the NO.sub.x change threshold module determines if the amount of
change in the NO.sub.x efficiency exceeds the NO.sub.x efficiency
change threshold using NO.sub.x efficiency determinations taken
while the engine output power parameter is within the engine output
power range.
6. The apparatus of claim 2, wherein the NO.sub.x module is
structured to determine that diluted reductant is in the SCR system
responsive to the engine output parameter below the output power
threshold and the NO.sub.x efficiency below the NO.sub.x efficiency
threshold.
7. The apparatus of claim 1, wherein the sampling window includes
at least one of a predefined window of time and a predefined number
of consecutive samples.
8. The apparatus of claim 1, wherein the NO.sub.x warning module is
structured to provide the NO.sub.x alarm to at least one of an
on-board detection ("OBD") system communicably coupled to the
apparatus and an external computer.
9. The apparatus of claim 1, further comprising a disable module
structured to limit an engine to a low output in response to
receiving the NO.sub.x alarm.
10. A system comprising: an engine; an exhaust aftertreatment
system in exhaust receiving communication with the engine; and a
controller communicably coupled to the engine and the exhaust
aftertreatment system, the controller structured to: determine an
amount of change in a nitrogen oxide ("NO.sub.x") efficiency of a
component of the exhaust aftertreatment system within a sampling
window; determine the amount of change in the NO.sub.x efficiency
exceeds a NO.sub.x efficiency change threshold; and provide a
NO.sub.x alarm in response to a NO.sub.x efficiency below a
NO.sub.x efficiency threshold and the amount of change in the
NO.sub.x efficiency exceeding the NO.sub.x efficiency change
threshold.
11. The system of claim 10, wherein the component includes a
selective catalytic reduction ("SCR") system.
12. The system of claim 11, wherein the controller is further
structured to determine that diluted reductant is in the SCR system
responsive to an engine output parameter below an output power
threshold and the NO.sub.x efficiency below the NO.sub.x efficiency
threshold.
13. The system of claim 12, wherein one or more of: the engine
output power parameter includes revolutions per minute ("RPM") of
an engine and the output power threshold includes an RPM threshold;
the engine output power parameter includes an engine power output
level of the engine and the output power threshold includes a level
of engine power output; the engine output power parameter includes
a temperature of the engine and the output power threshold includes
a temperature threshold; the engine output power parameter includes
torque of the engine and the output power threshold includes a
torque threshold; and the engine output power parameter comprises a
level of exhaust flow and the output power threshold comprises an
engine exhaust level threshold.
14. The system of claim 13, wherein the controller is structured to
determine the engine output power parameter at a sampling rate,
wherein the sampling rate includes one of a constant rate or a rate
triggered by at least one engine operating parameter, the at least
one engine operating parameter including at least one of a
predefined engine power output level and a predefined engine
speed.
15. The system of claim 10, wherein the sampling window includes at
least one of a predefined window of time and a predefined number of
consecutive samples.
16. A method comprising: determining an amount of change in a
nitrogen oxide ("NOx") efficiency of a component of an exhaust
aftertreatment system within a sampling window; determining the
amount of change in the NOx efficiency exceeds a NOx efficiency
change threshold; and providing a NOx alarm in response to a NOx
efficiency below a NOx efficiency threshold and the amount of
change in the NOx efficiency exceeding the NOx efficiency change
threshold.
17. The method of claim 16, wherein the component includes a
selective catalytic reduction ("SCR") system, and the method
further includes determining that diluted reductant is in the SCR
system responsive to an engine output parameter below an output
power threshold and the NO.sub.x efficiency below the NO.sub.x
efficiency threshold.
18. The method of claim 16, wherein the sampling window includes at
least one of a predefined window of time and a predefined number of
consecutive samples.
19. The method of claim 16, further comprising limiting an engine
to a low output in response to receiving the NO.sub.x alarm.
20. The method of claim 16, wherein providing the NO.sub.x alarm
includes at least one of providing the NO.sub.x alarm to an
on-board detection ("OBD") system and providing the NO.sub.x alarm
to an external computer relative to an apparatus embodying the
exhaust aftertreatment system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/934,143, filed on Jul. 2, 2013, which
claims the benefit of U.S. Provisional Patent Application No.
61/788,546, filed on Mar. 15, 2013, both of which are incorporated
herein by reference in their entireties.
FIELD
[0002] This invention relates to exhaust aftertreatment systems and
more particularly relates to determining if diluted reductant is
used in the exhaust aftertreatment systems.
BACKGROUND
[0003] Internal combustion engines emit gases and particulate that
are considered a pollutant to the environment. The U.S.
Environmental Protection Agency ("EPA") regulates what internal
combustion engines are allowed to emit and has specific regulations
for actions to happen if an engine exceeds the emissions
regulations. One requirement for diesel engines and gasoline
engines run lean is that a reductant fluid of a specific
concentration is to be injected into the exhaust gas stream to
reduce nitrogen oxide ("NOx") emissions. The EPA also requires that
a vehicle be limited in speed if the reductant fluid is diluted
above a specific level.
SUMMARY
[0004] An apparatus for diagnosing an exhaust aftertreatment
component is disclosed. A system and method also perform the
functions of the apparatus. The apparatus includes, in one
embodiment, an engine output module that determines an engine
output power parameter. The engine output power parameter is for an
engine. The apparatus, in another embodiment, includes an output
power threshold module that determines if the engine output power
parameter is below an output power threshold. The apparatus also
includes, in another embodiment, a NOx module that determines a
nitrogen oxide ("NOx") efficiency of a selective catalytic
reduction ("SCR") system in response to the output power threshold
module determining that the determined engine output power
parameter is below the output power threshold. The SCR system is in
exhaust receiving communication with the engine. In another
embodiment, the apparatus includes a NOx threshold module that
determines if the NOx efficiency is below a NOx efficiency
threshold, and a NOx warning module that sends a NOx alarm signal
in response to the NOx threshold module determining that the NOx
efficiency is below the NOx efficiency threshold.
[0005] In one embodiment, the apparatus includes a NOx change
module and a NOx change threshold module. The NOx change module
determines an amount of change in the NOx efficiency within a
sampling window, and the NOx change threshold module determines if
the amount of change in the NOx efficiency determined by the NOx
change module exceeds a NOx efficiency change threshold. In the
embodiment, the NOx warning module sends the NOx alarm signal in
response to the NOx threshold module determining that the NOx
efficiency is below the NOx efficiency threshold and the NOx change
threshold module determining that the amount of change in the NOx
efficiency exceeds the NOx efficiency change threshold.
[0006] In another embodiment, the NOx module determines the NOx
efficiency while the determined engine output power parameter is
within an engine output power range. The engine output power range
is a range below the output power threshold, and the NOx change
threshold module determines if the amount of change in the NOx
efficiency exceeds the NOx efficiency change threshold using NOx
efficiency determinations taken while the engine output power
parameter is within the engine output power range. In another
embodiment, the sampling window comprises a window of time or a
number of consecutive samples.
[0007] In one embodiment, the engine output power parameter
includes a level of exhaust flow of the engine and the output power
threshold is an engine exhaust level threshold. In a further
embodiment, the engine exhaust level threshold includes an engine
exhaust flow level that is below 50 percent of a maximum exhaust
flow level. In another embodiment, the engine output power
parameter includes revolutions per minute ("RPM") of the engine and
the output power threshold is an RPM threshold. In another
embodiment, the engine output power parameter includes an engine
power output level of the engine and the output power threshold is
a level of engine power output. In another embodiment, the engine
output power parameter includes a temperature of the engine and the
output power threshold is a temperature threshold. In another
embodiment, the engine output power parameter includes torque of
the engine and the output power threshold is a torque
threshold.
[0008] In one embodiment, the determined engine output power
parameter includes an exponential weighted moving average of the
determined engine output power parameter. In another embodiment,
the engine output module determines the engine output power
parameter in conjunction with a reductant tank refill event. In
another embodiment, the engine output module determines the engine
output power parameter at a sampling rate. In a further embodiment,
the engine output module determines the engine output power
parameter at the sampling rate during a period that the engine is
operating within a set of engine operating parameters. In another
embodiment, the apparatus includes a disable module that limits the
engine to a low output in response to receiving the NOx alarm
signal. In another embodiment, the NOx alarm signal comprises an
FC3543 code for diluted reductant.
[0009] A system includes an SCR system in exhaust receiving
communication with an engine, and a reductant dilution apparatus.
The reductant dilution apparatus includes an engine output module
that determines an engine output power parameter. The engine output
power parameter is for the engine. The reductant dilution
apparatus, in one embodiment, includes an output power threshold
module that determines if the engine output power parameter is
below an output power threshold. The reductant dilution apparatus
includes, in another embodiment, a NOx module that determines
nitrogen oxide ("NOx") efficiency of the SCR system in response to
the output power threshold module determining that the engine
output power parameter is below the output power threshold. The
reductant dilution apparatus includes, in another embodiment, a NOx
threshold module that determines if the NOx efficiency is below a
NOx efficiency threshold, and a NOx warning module that sends a NOx
alarm signal in response to the NOx threshold module determining
that the NOx efficiency is below the NOx efficiency threshold. In
one embodiment, the system includes the engine. In another
embodiment, the system includes a device powered by the engine.
[0010] A method for diagnosing an exhaust aftertreatment component
includes determining an engine output power parameter for an engine
and determining if the engine output power parameter is below an
output power threshold. The method includes determining a NOx
efficiency of an SCR system in response determining that the engine
output power parameter is below the output power threshold. The SCR
system is in exhaust receiving communication with the engine. The
method includes determining if the NOx efficiency is below a NOx
efficiency threshold, and sending a NOx alarm signal in response to
determining that the NOx efficiency is below the NOx efficiency
threshold.
[0011] In one embodiment, the method includes determining an amount
of change in the NOx efficiency within a sampling window, and
determining if the amount of change in the NOx efficiency exceeds a
NOx efficiency change threshold. In the embodiment, sending the NOx
alarm signal is in response to determining that the NOx efficiency
is below the NOx efficiency threshold and determining that the
amount of change in the NOx efficiency exceeds the NOx efficiency
change threshold. In another embodiment, determining the NOx
efficiency includes determining the NOx efficiency while the engine
output power parameter is within an engine output power range. The
engine output power range includes a range below the output power
threshold, and determining if the amount of change in the NOx
efficiency exceeds the NOx efficiency change threshold uses NOx
efficiency determinations taken while the engine output power
parameter is within the engine output power range. In another
embodiment, the engine output power parameter comprises a level of
exhaust flow of the engine and the output power threshold is an
engine exhaust level threshold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In order that the advantages of the invention will be
readily understood, a more particular description of the invention
briefly described above will be rendered by reference to specific
embodiments that are illustrated in the appended drawings.
Understanding that these drawings depict only typical embodiments
of the invention and are not therefore to be considered to be
limiting of its scope, the invention will be described and
explained with additional specificity and detail through the use of
the accompanying drawings, in which:
[0013] FIG. 1 is a schematic diagram of an engine system having an
internal combustion engine and an exhaust aftertreatment system in
accordance with one representative embodiment;
[0014] FIG. 2 is a schematic diagram of the exhaust aftertreatment
system of FIG. 1 in accordance with one representative
embodiment;
[0015] FIG. 3 is a diagram of NO.sub.x efficiency versus exhaust
gas flow;
[0016] FIG. 4 is a schematic block diagram of an apparatus with one
embodiment of a controller of the engine system of FIG. 1 in
accordance with one representative embodiment;
[0017] FIG. 5 is a schematic block diagram of an alternate
embodiment of an apparatus with another embodiment of a controller
of the engine system of FIG. 1 in accordance with one
representative embodiment;
[0018] FIG. 6 is a schematic block diagram illustrating one
embodiment of a method for diagnosing an exhaust aftertreatment in
accordance with one representative embodiment; and
[0019] FIG. 7 is a schematic block diagram illustrating another
embodiment of a method for diagnosing an exhaust aftertreatment in
accordance with one representative embodiment.
DETAILED DESCRIPTION
[0020] Reference throughout this specification to "one embodiment,"
"an embodiment," or similar language means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment. Thus,
appearances of the phrases "in one embodiment," "in an embodiment,"
and similar language throughout this specification may, but do not
necessarily, all refer to the same embodiment, but mean "one or
more but not all embodiments" unless expressly specified otherwise.
The terms "including," "comprising," "having," and variations
thereof mean "including but not limited to" unless expressly
specified otherwise. An enumerated listing of items does not imply
that any or all of the items are mutually exclusive and/or mutually
inclusive, unless expressly specified otherwise. The terms "a,"
"an," and "the" also refer to "one or more" unless expressly
specified otherwise.
[0021] Furthermore, the described features, advantages, and
characteristics of the embodiments may be combined in any suitable
manner. One skilled in the relevant art will recognize that the
embodiments may be practiced without one or more of the specific
features or advantages of a particular embodiment. In other
instances, additional features and advantages may be recognized in
certain embodiments that may not be present in all embodiments.
[0022] These features and advantages of the embodiments will become
more fully apparent from the following description and appended
claims, or may be learned by the practice of embodiments as set
forth hereinafter. As will be appreciated by one skilled in the
art, aspects of the present invention may be embodied as a system,
method, and/or computer program product. Accordingly, aspects of
the present invention may take the form of an entirely hardware
embodiment, an entirely software embodiment (including firmware,
resident software, micro-code, etc.) or an embodiment combining
software and hardware aspects that may all generally be referred to
herein as a "circuit," "module," or "system." Furthermore, aspects
of the present invention may take the form of a computer program
product embodied in one or more computer readable medium(s) having
program code embodied thereon.
[0023] Many of the functional units described in this specification
have been labeled as modules, in order to more particularly
emphasize their implementation independence. For example, a module
may be implemented as a hardware circuit comprising custom VLSI
circuits or gate arrays, off-the-shelf semiconductors such as logic
chips, transistors, or other discrete components. A module may also
be implemented in programmable hardware devices such as field
programmable gate arrays, programmable array logic, programmable
logic devices or the like.
[0024] Modules may also be implemented in software for execution by
various types of processors. An identified module of program code
may, for instance, comprise one or more physical or logical blocks
of computer instructions which may, for instance, be organized as
an object, procedure, or function. Nevertheless, the executables of
an identified module need not be physically located together, but
may comprise disparate instructions stored in different locations
which, when joined logically together, comprise the module and
achieve the stated purpose for the module.
[0025] Indeed, a module of program code may be a single
instruction, or many instructions, and may even be distributed over
several different code segments, among different programs, and
across several memory devices. Similarly, operational data may be
identified and illustrated herein within modules, and may be
embodied in any suitable form and organized within any suitable
type of data structure. The operational data may be collected as a
single data set, or may be distributed over different locations
including over different storage devices, and may exist, at least
partially, merely as electronic signals on a system or network.
Where a module or portions of a module are implemented in software,
the program code may be stored and/or propagated on in one or more
computer readable medium(s).
[0026] The computer readable medium may be a tangible computer
readable storage medium storing the program code. The computer
readable storage medium may be, for example, but not limited to, an
electronic, magnetic, optical, electromagnetic, infrared,
holographic, micromechanical, or semiconductor system, apparatus,
or device, or any suitable combination of the foregoing.
[0027] More specific examples of the computer readable storage
medium may include but are not limited to a portable computer
diskette, a hard disk, a random access memory ("RAM"), a read-only
memory ("ROM"), an erasable programmable read-only memory ("EPROM"
or Flash memory), a portable compact disc read-only memory
("CD-ROM"), a digital versatile disc ("DVD"), an optical storage
device, a magnetic storage device, a holographic storage medium, a
micromechanical storage device, or any suitable combination of the
foregoing. In the context of this document, a computer readable
storage medium may be any tangible medium that can contain, and/or
store program code for use by and/or in connection with an
instruction execution system, apparatus, or device.
[0028] The computer readable medium may also be a computer readable
signal medium. A computer readable signal medium may include a
propagated data signal with program code embodied therein, for
example, in baseband or as part of a carrier wave. Such a
propagated signal may take any of a variety of forms, including,
but not limited to, electrical, electro-magnetic, magnetic,
optical, or any suitable combination thereof. A computer readable
signal medium may be any computer readable medium that is not a
computer readable storage medium and that can communicate,
propagate, or transport program code for use by or in connection
with an instruction execution system, apparatus, or device. Program
code embodied on a computer readable signal medium may be
transmitted using any appropriate medium, including but not limited
to wire-line, optical fiber, Radio Frequency ("RF"), or the like,
or any suitable combination of the foregoing.
[0029] In one embodiment, the computer readable medium may comprise
a combination of one or more computer readable storage mediums and
one or more computer readable signal mediums. For example, program
code may be both propagated as an electro-magnetic signal through a
fiber optic cable for execution by a processor and stored on RAM
storage device for execution by the processor.
[0030] Program code for carrying out operations for aspects of the
present invention may be written in any combination of one or more
programming languages, including an object oriented programming
language such as Java, Smalltalk, C++, PHP or the like and
conventional procedural programming languages, such as the "C"
programming language or similar programming languages. The program
code may execute entirely on the user's computer, partly on the
user's computer, as a stand-alone software package, partly on the
user's computer and partly on a remote computer or entirely on the
remote computer or server. In the latter scenario, the remote
compute may be connected to the user's computer through any type of
network, including a local area network ("LAN") or a wide area
network ("WAN"), or the connection may be made to an external
computer (for example, through the Internet using an Internet
Service Provider).
[0031] The computer program product may be shared, simultaneously
serving multiple customers in a flexible, automated fashion. The
computer program product may be standardized, requiring little
customization and scalable, providing capacity on demand in a
pay-as-you-go model. The computer program product may be stored on
a shared file system accessible from one or more servers.
[0032] The computer program product may be integrated into a
client, server and network environment by providing for the
computer program product to coexist with applications, operating
systems and network operating systems software and then installing
the computer program product on the clients and servers in the
environment where the computer program product will function.
[0033] In one embodiment software is identified on the clients and
servers including the network operating system where the computer
program product will be deployed that are required by the computer
program product or that work in conjunction with the computer
program product. This includes the network operating system that is
software that enhances a basic operating system by adding
networking features.
[0034] Furthermore, the described features, structures, or
characteristics of the embodiments may be combined in any suitable
manner. In the following description, numerous specific details are
provided, such as examples of programming, software modules, user
selections, network transactions, database queries, database
structures, hardware modules, hardware circuits, hardware chips,
etc., to provide a thorough understanding of embodiments. One
skilled in the relevant art will recognize, however, that
embodiments may be practiced without one or more of the specific
details, or with other methods, components, materials, and so
forth. In other instances, well-known structures, materials, or
operations are not shown or described in detail to avoid obscuring
aspects of an embodiment.
[0035] Aspects of the embodiments are described below with
reference to schematic flowchart diagrams and/or schematic block
diagrams of methods, apparatuses, systems, and computer program
products according to embodiments of the invention. It will be
understood that each block of the schematic flowchart diagrams
and/or schematic block diagrams, and combinations of blocks in the
schematic flowchart diagrams and/or schematic block diagrams, can
be implemented by program code. The program code may be provided to
a processor of a general purpose computer, special purpose
computer, sequencer, or other programmable data processing
apparatus to produce a machine, such that the instructions, which
execute via the processor of the computer or other programmable
data processing apparatus, create means for implementing the
functions/acts specified in the schematic flowchart diagrams and/or
schematic block diagrams block or blocks.
[0036] The program code may also be stored in a computer readable
medium that can direct a computer, other programmable data
processing apparatus, or other devices to function in a particular
manner, such that the instructions stored in the computer readable
medium produce an article of manufacture including instructions
which implement the function/act specified in the schematic
flowchart diagrams and/or schematic block diagrams block or
blocks.
[0037] The program code may also be loaded onto a computer, other
programmable data processing apparatus, or other devices to cause a
series of operational steps to be performed on the computer, other
programmable apparatus or other devices to produce a computer
implemented process such that the program code which executed on
the computer or other programmable apparatus provide processes for
implementing the functions/acts specified in the flowchart and/or
block diagram block or blocks.
[0038] The schematic flowchart diagrams and/or schematic block
diagrams in the Figures illustrate the architecture, functionality,
and operation of possible implementations of apparatuses, systems,
methods and computer program products according to various
embodiments of the present invention. In this regard, each block in
the schematic flowchart diagrams and/or schematic block diagrams
may represent a module, segment, or portion of code, which
comprises one or more executable instructions of the program code
for implementing the specified logical function(s).
[0039] It should also be noted that, in some alternative
implementations, the functions noted in the block may occur out of
the order noted in the Figures. For example, two blocks shown in
succession may, in fact, be executed substantially concurrently, or
the blocks may sometimes be executed in the reverse order,
depending upon the functionality involved. Other steps and methods
may be conceived that are equivalent in function, logic, or effect
to one or more blocks, or portions thereof, of the illustrated
Figures.
[0040] Although various arrow types and line types may be employed
in the flowchart and/or block diagrams, they are understood not to
limit the scope of the corresponding embodiments. Indeed, some
arrows or other connectors may be used to indicate only the logical
flow of the depicted embodiment. For instance, an arrow may
indicate a waiting or monitoring period of unspecified duration
between enumerated steps of the depicted embodiment. It will also
be noted that each block of the block diagrams and/or flowchart
diagrams, and combinations of blocks in the block diagrams and/or
flowchart diagrams, can be implemented by special purpose
hardware-based systems that perform the specified functions or
acts, or combinations of special purpose hardware and program
code.
[0041] FIG. 1 is a schematic diagram of an engine system 10 having
an internal combustion engine and an exhaust aftertreatment system
in accordance with one representative embodiment. The main
components of the engine system 10 include an internal combustion
engine 20 and an exhaust gas aftertreatment system 100 in exhaust
gas-receiving communication with the engine 20. The internal
combustion engine 20 can be a compression-ignited internal
combustion engine, such as a diesel fueled engine, or a
spark-ignited internal combustion engine, such as a gasoline fueled
engine operated lean. On the intake side, the engine system 10 can
include an air inlet 12, inlet piping 14, a turbocharger compressor
16, and an intake manifold 18. The intake manifold 18 includes an
outlet operatively coupled to compression chambers 22 of the
internal combustion engine 20 for introducing air into the
compression chambers 22.
[0042] Within the internal combustion engine 20, air from the
atmosphere is combined with fuel, and combusted, to power the
engine. The fuel comes from the fuel tank 50 through a fuel
delivery system including, in one embodiment, a fuel pump and
common rail 52 to the fuel injectors 54, which inject fuel into the
combustion chambers 22 of the engine 20. Fuel injection timing can
be controlled by the controller 40 via a fuel injector control
signal 84.
[0043] Combustion of the fuel and air in the compression chambers
22 produces exhaust gas that is operatively vented to an exhaust
manifold 30. From the exhaust manifold 30, a portion of the exhaust
gas may be used to power a turbocharger turbine 32. The
turbocharger turbine 32 drives the turbocharger compressor 16,
which may compress at least some of the air entering the air inlet
12 before directing it to the intake manifold 18 and into the
compression chambers 22 of the engine 20.
[0044] For the purposes of altering the combustion properties of
the engine 20, a portion of the exhaust gas may bypass the
turbocharger turbine 32 and be re-circulated to the engine 20 via
an exhaust gas recirculation ("EGR") line 36 and back to the inlet
piping 14. In one embodiment, an EGR valve 38 is actuated to divert
an amount of exhaust gas corresponding to a proportion set by a
controller 40 via an EGR control signal.
[0045] The portion of the exhaust gas which is not re-circulated to
the engine 20 via the EGR line 36 is destined for expulsion from
the engine system 10 into the atmosphere. Thus, the exhaust gas
stream flows from the exhaust manifold 30 or turbocharger turbine
32, through the exhaust piping 34, and through the exhaust gas
aftertreatment system 100 prior to being vented into the atmosphere
through tailpipe 35. The exhaust gas aftertreatment system 100 is
configured to remove various chemical compounds and particulate
emissions present in the exhaust gas received from the exhaust
manifold 30. Specifically, the exhaust gas treated in the exhaust
gas aftertreatment system 100 contains significantly fewer
pollutants, such as unburned hydrocarbons, CO, diesel particulate
matter, and NO.sub.x, than untreated exhaust gas.
[0046] Various sensors, such as temperature sensors 64, pressure
sensors 66, fuel sensor 72, exhaust gas flow sensors 74, 76 and the
like, may be strategically disposed throughout the engine system 10
and may be in communication with the controller 40 to monitor
operating conditions of the engine system 10. In one embodiment,
the exhaust gas flow sensor 74 senses the rate at which the exhaust
gas is flowing towards exhaust gas aftertreatment system 100.
[0047] Also, the engine system 10 may include an on-board
diagnostic ("OBD") system 90 in electronic communication with the
controller 40 via the control signal 91. Generally, the OBD system
90 is configured to alert a user (e.g., vehicle operator) of any
operating condition faults monitored and triggered by the
controller 40.
[0048] FIG. 2 is a schematic diagram of the exhaust aftertreatment
system 100 of FIG. 1 in accordance with one representative
embodiment. The exhaust gas aftertreatment system 100 includes the
controller 40, the OBD system 90, an oxidation catalyst 140, a
particulate matter ("PM") filter 142, an SCR system 150, and an
optional ammonia oxidation ("AMOX") catalyst 154. The SCR system
150 has a reductant delivery system 151 and an SCR catalyst 152.
The oxidation catalyst 140 can be any of various oxidation
catalysts known in the art, such as a non-methane hydrocarbon
catalyst. The PM filter 142 may be any of various particulate
matter or other filters known in the art.
[0049] In an exhaust flow direction, as indicated by directional
arrow 144, exhaust gas may flow from the exhaust piping 34, through
the oxidation catalyst 140, through the PM filter 142, through the
SCR catalyst 152, through the AMOX catalyst 154 if present, and
then be expelled into the atmosphere through the tailpipe 35. Thus,
in the illustrated embodiment the PM filter 142 is positioned
downstream of the oxidation catalyst 140, the SCR catalyst 152 is
positioned downstream of the PM filter 142, and the AMOX catalyst
154 is positioned downstream of the SCR catalyst 152. However,
other arrangements of the components of the exhaust gas
aftertreatment system 100 are also possible.
[0050] The oxidation catalyst 140 can have any of various
flow-through designs known in the art, such as conventional diesel
oxidation catalysts. Generally, the oxidation catalyst 140 is
configured to oxidize at least some particulate matter, e.g., the
soluble organic fraction of soot, in the exhaust and reduce
unburned hydrocarbons and CO in the exhaust to less environmentally
harmful compounds. For example, the oxidation catalyst 140 may
sufficiently reduce the hydrocarbon and CO concentrations in the
exhaust to meet the requisite emissions standards for those
components of the exhaust gas. An indirect consequence of the
oxidation capabilities of the oxidation catalyst 140 is the ability
of the oxidation catalyst to oxidize nitrogen monoxide ("NO") into
NO.sub.2. In this manner, the level of NO.sub.2 exiting the
oxidation catalyst 140 is equal to the NO.sub.2 in the exhaust gas
generated by the engine 20 plus the NO.sub.2 converted from NO by
the oxidation catalyst.
[0051] In addition to treating the hydrocarbon and CO
concentrations in the exhaust gas, the oxidation catalyst 140 can
also be used in the controlled regeneration of the PM filter 142
and the SCR catalyst 152. This can be accomplished through the
injection, or dosing, of unburned hydrocarbons "UHC" into the
exhaust gas upstream of the oxidation catalyst 140. Upon contact
with the oxidation catalyst 140, the UHC undergoes an exothermic
oxidation reaction which leads to an increase in the temperature of
the exhaust gas exiting the oxidation catalyst 140 and subsequently
entering the PM filter 142 and/or SCR catalyst 152. The amount of
UHC added to the exhaust gas is selected to achieve the desired
temperature increase or target controlled regeneration
temperature.
[0052] The PM filter 142 can be any of various flow-through designs
known in the art, including diesel particulate filters ("DPF"), and
configured to reduce particulate matter concentrations, e.g., soot
and ash, in the exhaust gas to meet requisite emission standards.
In addition, the exhaust gas aftertreatment system 100 can further
include a variety of sensors surrounding the PM filter 142 and
which are electrically coupled to the controller 40.
[0053] The SCR system 150 includes a reductant delivery system 151
comprising a reductant source 170, pump 180 and delivery mechanism
190. The reductant source 170 can be a container or tank capable of
retaining a reductant, such as, for example, ammonia ("NH.sub.3"),
urea, diesel fuel, or diesel oil. In one embodiment, the reductant
is called diesel exhaust fluid ("DEF"). The reductant source 170 is
in reductant supplying communication with the pump 180, which is
configured to pump reductant from the reductant source to the
delivery mechanism 190. The delivery mechanism 190 can include a
reductant injector schematically shown at 192 positioned upstream
of the SCR catalyst 152. The injector is selectively controllable
to inject reductant directly into the exhaust gas stream prior to
entering the SCR catalyst 152.
[0054] In some embodiments, the reductant can either be ammonia or
urea, which decomposes to produce ammonia. The ammonia reacts with
NO.sub.x in the presence of the SCR catalyst 152 to reduce the
NO.sub.x to less harmful emissions, such as N.sub.2 and H.sub.2O.
The NO.sub.x in the exhaust gas stream includes NO.sub.2 and NO.
Generally, both NO.sub.2 and NO are reduced to N.sub.2 and H.sub.2O
through various chemical reactions driven by the catalytic elements
of the SCR catalyst in the presence of NH.sub.3. However, as
discussed above, the chemical reduction of NO.sub.2 to N.sub.2 and
H.sub.2O typically is the most efficient chemical reaction.
Therefore, in general, the more NO.sub.2 in the exhaust gas stream
compared to NO, the more efficient the NO.sub.x reduction performed
by the SCR catalyst. Accordingly, the ability of the oxidation
catalyst 140 to convert NO to NO.sub.2 directly affects the
NO.sub.x reduction efficiency of the SCR system 150. Put another
way, the NO.sub.x reduction efficiency of the SCR system 150
corresponds at least indirectly to the condition or performance of
the oxidation catalyst 140. For example, a poorly performing (e.g.,
poorly conditioned) oxidation catalyst 140 may be more to blame for
the presence of excess NO.sub.x exiting the tailpipe than any
deficiencies associated with the SCR system 150. Therefore, the SCR
system 150, in one embodiment, (and the associated NO.sub.x
reduction performance of the SCR system 150) can act as a sensor to
determine the condition of the oxidation catalyst 140.
[0055] Additionally, as discussed above, some PM filters oxidize NO
to form NO.sub.2 independent of the oxidation catalyst.
Accordingly, a poorly performing (e.g., poorly conditioned) PM
filter 142 may be more to blame for the presence of excess NO.sub.x
exiting the tailpipe than any deficiencies associated with the SCR
system 150. For this reason, the SCR system 150 can act as a sensor
to determine the condition of the PM filter 142.
[0056] The SCR catalyst 152 can be any of various catalysts known
in the art. For example, in some implementations, the SCR catalyst
152 is a vanadium-based catalyst, and in other implementations, the
SCR catalyst is a zeolite-based catalyst, such as a Cu-Zeolite or a
Fe-Zeolite catalyst. In one representative embodiment, the
reductant is aqueous urea and the SCR catalyst 152 is a
zeolite-based catalyst.
[0057] The AMOX catalyst 154 can be any of various flow-through
catalysts configured to react with ammonia to produce mainly
nitrogen. Generally, the AMOX catalyst 154 is utilized to remove
ammonia that has slipped through or exited the SCR catalyst 152
without reacting with NO.sub.x in the exhaust. In certain
instances, the exhaust gas aftertreatment system 100 can be
operable with or without an AMOX catalyst 154. Further, although
the AMOX catalyst 154 is shown as a separate unit from the SCR
catalyst 152, in some implementations, the AMOX catalyst 154 can be
integrated with the SCR catalyst, e.g., the AMOX catalyst 154 and
the SCR catalyst 152 can be located within the same housing.
[0058] The embodiment of the exhaust aftertreatment system 100
illustrated in FIG. 2 incorporates multiple NO.sub.x sensors, which
measure the amount (e.g., flow rate) of NO.sub.x in the exhaust gas
throughout the exhaust treatment process. In some implementations,
the exhaust aftertreatment system 100 may include one or more of an
engine out NO.sub.x sensor 162A upstream of the oxidation catalyst
140 and downstream of the engine 20, an SCR mid-bed NO.sub.x sensor
162B embedded within the SCR catalyst 152, a tailpipe NO.sub.x
sensor 162C downstream of the SCR catalyst 152 (and downstream of
the AMOX catalyst 154 in some embodiments). In one embodiment, the
mid-bed NO.sub.x sensor 162B measures NO.sub.x where the exhaust
enters the SCR catalyst 152.
[0059] The exhaust aftertreatment system 100 can also utilize
various other sensors for detecting corresponding characteristics
of the exhaust gas or components. For example, the illustrated
exhaust gas aftertreatment system 100 may include one or more of an
SCR inlet temperature sensor 164A upstream of the SCR catalyst, an
SCR mid-bed temperature sensor 164B embedded within the SCR
catalyst, an SCR outlet temperature sensor 164C downstream of the
SCR catalyst, an SCR inlet NH.sub.3 sensor 168A upstream of the SCR
catalyst 152, and an SCR outlet NH.sub.3 sensor 168B located
downstream of the SCR catalyst, and the like. In some cases, a
NO.sub.x sensor and an NH.sub.3 sensor may be combined into a dual
ammonia-NO.sub.x sensor (not shown). The various sensors may be in
electrical communication with the controller 40 to allow the
controller monitor the operating conditions of the exhaust gas
aftertreatment system 100 of the engine system 10.
[0060] Although the exhaust gas aftertreatment system 100 shown
includes one of an oxidation catalyst 140, PM filter 142, SCR
catalyst 152, and AMOX catalyst 154 positioned in specific
locations relative to each other along the exhaust flow path, in
other embodiments, the exhaust gas aftertreatment system 100 may
include more than one of any of the various catalysts positioned in
any of various positions relative to each other along the exhaust
flow path as desired. Further, although the oxidation catalyst 140
and AMOX catalyst 154 are non-selective catalysts, in some
embodiments, the oxidation and AMOX catalysts 140, 154 can be
selective catalysts.
[0061] The controller 40 controls the operation of the engine
system 10 and associated sub-systems, such as the internal
combustion engine 20 and the exhaust gas aftertreatment system 100.
The controller 40 is depicted in FIGS. 1 and 2 as a single physical
unit, but can include two or more physically separated units or
components in some embodiments if desired. Generally, the
controller 40 receives multiple inputs, processes the inputs, and
transmits multiple outputs. The multiple inputs may include sensed
measurements from the sensors and various user inputs. The inputs
are processed by the controller 40 using various algorithms, stored
data, and other inputs to update the stored data and/or generate
output values. The generated output values and/or commands are
transmitted to other components of the controller and/or to one or
more elements of the engine system 10 to control the system to
achieve desired results, and more specifically, achieve desired
exhaust gas emissions.
[0062] For example, the operating conditions of the internal
combustion engine 20 and the exhaust gas aftertreatment system 100
can be ascertained from any of the sensors or from the controller's
40 commands to the engine regarding the fraction of exhaust gas
recirculation, injection timing, and the like. In one embodiment,
information is gathered regarding, for example, fuel rate, engine
speed, engine load, the timing at which fuel injection timing is
advanced or retarded ("SOI," or start of injection), the fraction
of exhaust gas recirculation, driving conditions, exhaust flow
rate, the amount of O.sub.2, NO.sub.x (e.g., "NO.sub.2" and "NO"),
and NH.sub.3 in the exhaust gas, and exhaust gas temperatures and
pressures at various locations within the exhaust gas
aftertreatment system 100.
[0063] The controller 40 includes various modules for controlling
the operation of the engine system 10. For example, the controller
40 includes one or more modules for controlling the operation of
the internal combustion engine 20. The controller 40 further
includes one or more modules for controlling the operation and
regeneration of the SCR system 150. Additionally, the controller 40
include one or more modules for diagnosing the performance or
conditions of one or more components of the exhaust gas
aftertreatment system 100, and reporting the diagnosed performance
or conditions to the OBD system 90.
[0064] As is known in the art, the controller 40 and its various
modular components may comprise processor, memory, and interface
modules that may be fabricated of semiconductor gates on one or
more semiconductor substrates. Each semiconductor substrate may be
packaged in one or more semiconductor devices mounted on circuit
cards. Connections between the modules may be through semiconductor
metal layers, substrate-to-substrate wiring, or circuit card traces
or wires connecting the semiconductor devices.
[0065] A potential problem with the SCR system 150 is that the
reductant source 170 may include reductant that is diluted, for
example with water. Diluted reductant typically causes the SCR
system 150 to operate less efficiently. Typically, diluted
reductant causes the NO.sub.x efficiency to be reduced. Currently,
diluted reductant is difficult to distinguish from other failures
in the SCR system 150.
[0066] FIG. 3 is a diagram 300 of NO.sub.x efficiency versus
exhaust gas flow. The vertical axis 302 represents increasing SCR
NO.sub.x conversion (i.e. increasing NO.sub.x efficiency) and the
horizontal axis 304 represents increasing exhaust gas flow. The
sloping line 306 represents a typical NO.sub.x conversion
efficiency for a particular field aged an SCR system 150. The
sloping line 306 may represent an aged SCR system 150 that is
nearing end-of-life. The horizontal line 307 at the top of the
diagram represents a new SCR system 150. A first operating point
308 represents an operating condition for the engine 20 where the
exhaust gas output is relatively low and is below an engine exhaust
level threshold 310. The diagram 300 also includes a line that
represents a NO.sub.x efficiency threshold 312. Note that the
sloping line 306 for the field aged SCR system 150 extends below
the NO.sub.x efficiency threshold 312 for high exhaust gas flow
conditions. The second operating point 314 indicates a condition
where the exhaust gas flow is the same as for the first operating
point 308, but is below the NO.sub.x efficiency threshold 312. The
second operating point 314 may indicate a condition where the
reductant is diluted.
[0067] Note that for higher exhaust flow condition, a third
operating point 316 may be above the NO.sub.x efficiency threshold
312, but a fourth operating point 318 for an even higher exhaust
flow condition for the SCR system 150 is below the NO.sub.x
efficiency threshold 312. In a condition where the controller 40
samples NO.sub.x efficiency, the third operating point 316 may be a
sampled point and may indicate that the SCR system 150 is operating
normally and then at the next sampling time, exhaust gas flow may
be increased so that the fourth operating point 318 is the next
sampling point and is below the NO.sub.x efficiency threshold 312.
The controller 40 may then signal that the SCR system 150 is
operating below the NO.sub.x efficiency threshold 312. Thus where
exhaust gas flow is not accounted for, and aged SCR system 150 may
not be able to distinguish between a condition of a diluted
reductant and a condition where the exhaust gas flow is high. Other
failures in the SCR system 150 may also cause the SCR system 150
operate below the NO.sub.x efficiency threshold 312 and begin may
not be distinguished from the condition of diluted reductant.
[0068] One representative embodiment of an apparatus to diagnose a
diluted reductant condition may include a requirement sampling
NO.sub.x efficiency at a low exhaust gas flow condition. In another
embodiment, the apparatus may include a combination of a NO.sub.x
efficiency below the NO.sub.x efficiency threshold 312 and a step
change that is a decrease in NO.sub.x efficiency greater than a
certain amount. A step change is shown in the diagram 300 that may
indicate a NO.sub.x efficiency change threshold 320.
[0069] While FIG. 3 indicates a correlation between exhaust gas
flow and NO.sub.x efficiency for an SCR system 150, other measured
parameters for the engine 20 may also include a correlation between
NO.sub.x efficiency for the SCR system 150 and another engine
output power parameter, such as an amount of power output by the
engine 20, torque, engine temperature, engine speed, and the like.
One of skill in the art will recognize other engine power
parameters that correlate with NO.sub.x efficiency for an SCR
system 150 that has a characteristic of decreased NO.sub.x
efficiency for higher engine output power parameters.
[0070] FIG. 4 is a schematic block diagram of an apparatus 400 with
one embodiment of a controller 40 of the engine system 10 of FIG. 1
in accordance with one representative embodiment. The apparatus 400
includes a controller 40 with an engine output module 402, an
output power threshold module 404, a NO.sub.x module 406, a
NO.sub.x threshold module 408, and a NO.sub.x warning module 410,
which are described below.
[0071] In one embodiment, the apparatus 400 includes an engine
output module 402 that determines an engine output power parameter
for the engine 20. The engine output power parameter, in one
embodiment, is a determination of a level of exhaust flow of the
engine 20. The engine exhaust flow level may be determined from a
measurement from the exhaust gas flow sensor 74 as the exhaust gas
travels through the exhaust piping 34. In another embodiment, the
engine output power parameter includes revolutions per minute
("RPM" or engine speed) of the engine 20. An RPM sensor may be used
to determine RPM of the engine 20. In another embodiment, the
engine output power parameter includes an engine power output level
of the engine 20. For example, the engine power output level may be
in horsepower or other suitable power unit. Output power may be
determined by the controller 40 by measuring various engine
parameters indicative of power. In another embodiment, the engine
output power parameter includes a temperature of the engine 20. For
example, temperature sensors 64 for the engine 20 and related parts
may be used to determine temperature of the engine 20. In another
embodiment, the engine output power parameter includes torque of
the engine 20. One or more sensors may be used to determine torque
of the engine 20.
[0072] In one embodiment, the engine output module 402 determines
the engine output power parameter at a sampling rate. The sampling
rate may be constant or may be tied to other engine operating
parameters, such as operating at a certain output power level, a
certain RPM, etc. In one embodiment, the determined engine output
power parameter includes an exponential weighted moving average
("EWMA") of the determined engine output power parameter. Using an
EWMA may allow measurements or samples that are affected by
transients or other abnormal conditions to be averaged in with
other measurements and/or samples to avoid false triggers. As used
herein, the engine output power parameter may be a single
measurement or may be an average of several samples or measurements
using an EWMA or other averaging method. In another embodiment, the
engine output module 402 determines the engine output power
parameter at the sampling rate during a period that the engine is
operating within a set of engine operating parameters. For example,
the engine operating parameters may exclude extreme conditions or
conditions such as idling, high output associated with a steep
incline, startup, etc. For instance, certain systems may not be
operating during startup or other times and the engine output
module 402 may sample when the various systems are operational. In
one embodiment, the engine output module 402 may sample or
determine the engine output power parameter after a reductant tank
refill event.
[0073] In one embodiment, the apparatus 400 includes an output
power threshold module 404 that determines if the measured engine
output power parameter is below an output power threshold. In one
embodiment, the output power threshold is an engine exhaust level
threshold 310. For example, the engine exhaust level threshold 310
may be an engine exhaust flow level that is below 50 percent of a
maximum exhaust flow level. In an embodiment, where the engine
output power parameter is revolutions per minute ("RPM") of the
engine 20, the output power threshold may be an RPM threshold. In
another embodiment where the engine output power parameter is an
engine power output level of the engine 20, the output power
threshold may be a level of engine power output. Where the engine
output power parameter is a temperature of the engine 20, the
output power threshold may be a temperature threshold. Where the
engine output power parameter is torque of the engine 20, the
output power threshold may be a torque threshold. One of skill in
the art will recognize other engine output power parameters and
appropriate thresholds.
[0074] In one embodiment, the apparatus 400 includes a NO.sub.x
module 406 that determines a NO.sub.x efficiency of the SCR system
150 in response to the output power threshold module 404
determining that the engine output power parameter is below the
output power threshold. In another embodiment, the apparatus 400
includes a NO.sub.x threshold module 408 that determines if the
NO.sub.x efficiency is below a NO.sub.x efficiency threshold 312.
For example, when exhaust gas flow is the output power parameter,
the NO.sub.x module 406 may determine NO.sub.x efficiency for
various sampling points that occur when the output power threshold
module 404 determines that the exhaust gas flow level is below and
engine exhaust level threshold 310. The NO.sub.x threshold module
408 may determine that the NO.sub.x efficiency is above the
NO.sub.x efficiency threshold 312, for example when the reductant
is not diluted. Other sampling points that occur while the engine
20 is operating at an exhaust gas flow level above the engine
exhaust level threshold 310 may be ignored or may be used for a
different purpose by the controller 40.
[0075] For another sampling point where the output power threshold
module 404 determines that the engine output power parameter is
below the output power threshold, the NO.sub.x threshold module 408
may determine that the NO.sub.x efficiency determined by the
NO.sub.x module 406 is below the NO.sub.x efficiency threshold 312,
for example while diluted reductant is in the SCR system 150. While
the engine output power parameter is below the output power
threshold, one typical condition where the SCR system 150 will have
a NO.sub.x efficiency above the NO.sub.x efficiency threshold 312
and then have a NO.sub.x efficiency below the NO.sub.x efficiency
threshold 312 is when the reductant source 170 (i.e. a tank)
becomes diluted when refilled. Other failures may also cause this
condition as well. Other sensors may be used to detect other
failures to possibly distinguish between diluted reductant and
other failures. In one embodiment, the engine output module 402
determines or samples the engine output power parameter after a
reductant tank refill event and when the engine output power
parameter is below the output power threshold. The NO.sub.x
threshold module 408 may then compare NO.sub.x efficiencies after
another reductant refill event, which may correlate NO.sub.x
efficiencies below the NO.sub.x efficiency threshold 312 to a
reductant tank refill event. This sampling after a refill event may
increase the likelihood that a NO.sub.x efficiency below the
NO.sub.x efficiency threshold 312 is related to diluted
reductant.
[0076] The apparatus 400, in one embodiment, includes a NO.sub.x
warning module 410 that sends a NO.sub.x alarm signal in response
to the NO.sub.x threshold module 408 determining that the NO.sub.x
efficiency is below the NO.sub.x efficiency threshold 312. For
example, the NO.sub.x alarm signal may be an FC3543 code for
diluted reductant, as mandated by the EPA. The NO.sub.x warning
module may send the NO.sub.x alarm signal to the controller 40. In
another embodiment, the NO.sub.x warning module 410 sends the
NO.sub.x alarm signal to the OBD system 90 as an OBD signal 414 to
display a warning on a display panel. In another embodiment, the
NO.sub.x alarm signal is sent over a computer network, such as a
wireless or cellular network, to a server or other computer. One of
skill in the art will recognize other NO.sub.x alarm signals and
destinations.
[0077] FIG. 5 is a schematic block diagram of an alternate
embodiment of an apparatus 500 with another embodiment of a
controller 40 of the engine system of FIG. 1 in accordance with one
representative embodiment. The apparatus 500 includes a controller
40 with an engine output module 402, an output power threshold
module 404, a NO.sub.x module 406, a NO.sub.x threshold module 408,
and a NO.sub.x warning module 410, which are substantially similar
to those described in relation to the apparatus 400 of FIG. 4. The
apparatus 500, in various embodiments, may also include a
controller 40 with a NO.sub.x change module 502, a NO.sub.x change
threshold module 504, and a disable module 506, which are described
below.
[0078] In one embodiment, the apparatus 500 includes a NO.sub.x
change module 502 and a NO.sub.x change threshold module 504. The
NO.sub.x change module 502 determines an amount of change in the
NO.sub.x efficiency within a sampling window and the NO.sub.x
change threshold module 504 determines if the amount of change in
the NO.sub.x efficiency determined by the NO.sub.x change module
exceeds a NO.sub.x efficiency change threshold 320. In one example,
the NO.sub.x warning module 410 sends the NO.sub.x alarm signal in
response to the NO.sub.x threshold module 408 determining that the
NO.sub.x efficiency is below the NO.sub.x efficiency threshold and
the NO.sub.x change threshold module 504 determining that the
amount of change in the NO.sub.x efficiency exceeds the NO.sub.x
efficiency change threshold 320. In the example, a NO.sub.x
efficiency change exceeding the NO.sub.x efficiency change
threshold 320 may be related to an engine condition that may be
unrelated to detecting diluted reductant and triggering the
NO.sub.x warning module 410 to send the NO.sub.x alarm signal may
be more accurate when both the NO.sub.x efficiency threshold 312
and the NO.sub.x efficiency change threshold 320 are exceeded. In
another example, the NO.sub.x warning module 410 sends the NO.sub.x
alarm signal in response to either the NO.sub.x threshold module
408 determining that the NO.sub.x efficiency is below the NO.sub.x
efficiency threshold or the NO.sub.x change threshold module 504
determining that the amount of change in the NO.sub.x efficiency
exceeds the NO.sub.x efficiency change threshold 320.
[0079] In one embodiment, the sampling window is a window of time.
In another embodiment, the sampling window is a number of
consecutive samples. In another embodiment, the NO.sub.x module 406
determines the NO.sub.x efficiency while the engine output power
parameter is within an engine output power range. The engine output
power range may include a range that is below the output power
threshold. For example, the NO.sub.x module 406 may determine the
NO.sub.x efficiency at several operating points within the engine
output power range while the reductant is not diluted. The NO.sub.x
module 406 may determine a NO.sub.x efficiency while the engine 20
is operating in the engine output power range and the NO.sub.x
change threshold module 504 may then determine if the amount of
change in the NO.sub.x efficiency exceeds the NO.sub.x efficiency
change threshold 320 using NO.sub.x efficiency determinations taken
while the engine output power parameter is within the engine output
power range.
[0080] In one embodiment, the apparatus 500 includes a disable
module 506 that limits the engine 20 to a low output in response to
receiving the NO.sub.x alarm signal. For example, the disable
module 506 may limit a vehicle powered by the engine 20 to a speed
of 5 miles per hour. In another embodiment, the disable module 506
may not allow the engine 20 to start after receiving the NO.sub.x
alarm signal and then being turned off. The disable module 506, in
one embodiment, may take action to comply with requirements of the
EPA. In another embodiment, the disable module 506 may allow a
certain number of NO.sub.x alarm signals before disabling the
vehicle. For example, the NO.sub.x warning module 410 may send the
NO.sub.x alarm signal in the form of an OBD signal 414 to be
displayed to a user of the engine 20 and the disable module 506 may
not act on the first NO.sub.x alarm signal and then the disable
module 506 may limit the vehicle on a second NO.sub.x alarm signal.
In other embodiments, additional NO.sub.x alarm signals may be
ignored by the disable module 506 and/or controller 40 before the
disable module 506 limits the vehicle. One of skill in the art will
recognize other ways to for the disable module 506 to limit a
vehicle or device powered by the engine 20.
[0081] FIG. 6 is a schematic block diagram illustrating one
embodiment of a method 600 for diagnosing an exhaust aftertreatment
in accordance with one representative embodiment. The method 600
begins and determines 602 an engine output power parameter for the
engine 20 and determines 604 if the engine output power parameter
is below an output power threshold. If the method 600 determines
604 that the engine output power parameter is not below the output
power threshold, the method 600 returns and again determines 602 an
engine output power parameter. If the method 600 determines 604
that the engine output power parameter is below the output power
threshold, the method determines 606 a NO.sub.x efficiency of the
SCR system 150. The method 600 determines 608 if the NO.sub.x
efficiency is below a NO.sub.x efficiency threshold 312. If the
method 600 determines 608 that the NO.sub.x efficiency is not below
a NO.sub.x efficiency threshold 312, the method 600 returns and
again determines 602 an engine output power parameter. If the
method 600 determines 608 that the NO.sub.x efficiency is below a
NO.sub.x efficiency threshold 312, the method 600 sends 610 a
NO.sub.x alarm signal, and the method 600 ends. One or more of the
engine output module 402, the output power threshold module 404,
the NO.sub.x module 406, the NO.sub.x threshold module 408, and the
NO.sub.x warning module 410 may be employed to perform the steps of
the method 600.
[0082] FIG. 7 is a schematic block diagram illustrating another
embodiment of a method 700 for diagnosing an exhaust aftertreatment
in accordance with one representative embodiment. The method 700
begins and determines 702 an engine output power parameter for the
engine 20 and determines 704 if the engine output power parameter
is below an output power threshold. If the method 700 determines
704 that the engine output power parameter is not below the output
power threshold, the method 700 returns and again determines 702 an
engine output power parameter. If the method 700 determines 704
that the engine output power parameter is below the output power
threshold, the method determines 706 a NO.sub.x efficiency of the
SCR system 150. The method 700 determines 708 if the NO.sub.x
efficiency is below a NO.sub.x efficiency threshold 312. If the
method 700 determines 708 that the NO.sub.x efficiency is not below
a NO.sub.x efficiency threshold 312, the method 700 returns and
again determines 602 an engine output power parameter.
[0083] If the method 700 determines 708 that the NO.sub.x
efficiency is below a NO.sub.x efficiency threshold 312, determines
710 an amount of change in the NO.sub.x efficiency within a
sampling window. The method 700 determines 712 if the amount of
change in the NO.sub.x efficiency exceeds a NO.sub.x efficiency
change threshold 320. If the method 700 determines 712 that the
amount of change in the NO.sub.x efficiency does not exceed a
NO.sub.x efficiency change threshold 320, the method 700 returns
and again determines 702 an engine output power parameter. If the
method 700 determines 712 that the amount of change in the NO.sub.x
efficiency exceeds the NO.sub.x efficiency change threshold 320,
the method 700 sends 714 a NO.sub.x alarm signal and limits 716 the
engine 20 to a low output, and the method 700 ends. One or more of
the engine output module 402, the output power threshold module
404, the NO.sub.x module 406, the NO.sub.x threshold module 408,
the NO.sub.x warning module 410, the NO.sub.x change module 502,
the NO.sub.x change threshold module 504, and the disable module
506 may be employed to perform the steps of the method 700.
[0084] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
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